DVAJ-164 My sister sneaks into my futon without asking Nananami Kawakami

The entire story is from the younger brother's perspective. The tale of my sister and me! That day, I hugged her to comfort her while she was crying, and then she kissed me... Since then, it feels like I've been made her boyfriend stand-in. Even though I know this relationship is wrong! My lower half keeps reacting strongly. Today, my sister crawled into my bed again. Lately, she's been coming into my room and bathroom so casually, and soon my self-control will... collapse...